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Clean Up the Water with Cover Crops

Tipton Creek and the Southfork Watershed have been landmarks of his landscape since Al Kadolph grew up on this Hubbard, Iowa, farm. “Grandpa gave me a start in full-time farming by renting me his farm in 1982,” the fourth-generation farmer says.  

The South Fork of the Iowa River, along with Tipton Creek and Beaver Creek, drains about 200,000 acres in four north-central Iowa counties. It’s intensively farmed, with 840,000 head of swine and 85% of its acres in a corn-soybean rotation.

In 1999, Kadolph joined with neighbors to form the first farmer-led watershed conservation group in Iowa, the Southfork Watershed Alliance (SFWA). Today, he’s vice president of SFWA, a diverse mix of farmers, business leaders, government, and landowners. Together, they’ve added grass waterways, terraces, and buffer strips. “Farming’s changed from the chisel-plowing-soybean-ground mind-set of the 1960s,” he says.

To promote their efforts and to attract members, the SFWA hosted its third River Float and Water Quality Showcase on August 2. Participants enjoyed a meal afterward at the Steamboat Rock Boat Club in Pine Ridge Park overlooking the scenic Iowa River. 

As Roger Wolf, Iowa Soybean Association (ISA) director of environmental programs and services, spoke to the group, the water emergency precipitated by algae blooms on Lake Erie cast an eerie shadow over the progress that the SFWA, ISA, and corn and soybean producers planned to showcase that day.

“We know we have big issues downstream,” Wolf said. “How do we engage more farmers to improve productivity and save nutrients? Iowa’s goal is to reduce nutrient loads by 41%. Farmers would rather put lost nutrients into crops. If we’re serious about water quality, we have to work together and organize local leadership. The South Fork is important nationally. It’s a high-yielding, nutrient-rich watershed. On-farm research by USDA-ARS and others on this watershed and on 14 other watersheds across the U.S. will offer new data to help farmers make sound business decisions to reduce soil erosion and nutrient loss.” 

A groundswell of conservation is crucial to meeting the challenge. A majority of land in the 12 states in the Mississippi River Basin, the world’s fourth largest watershed, is farmed. Agriculture is the source of 71% of the nitrogen and 80% of phosphorus in the Gulf. The combination creates algae blooms and a toxic condition known as hypoxia. 

This past year, the SFWA was awarded state grants to install blind intakes, filter strips, and filter socks. Kadolph knows more is needed. This year, for the first time, he’s planting a cover crop. 

He’s not alone. When $1.4 million in cost-share funds was offered, most was claimed within five days by farmers planting their first cover crop. No promotional radio ads were run. “Cover crops can be a game changer, if we can make them work,” Wolf says.

Complex Issue Requires Suite of Solutions

Cover crops aren’t new. They’re getting a second look because studies show they reduce erosion and losses of nitrogen and phosphorus from soil. Iowa State University (ISU) data indicates that planting rye after corn harvest would cut nitrogen leaching by 31%.

However, a 2013 report from the National Wildlife Federation called Counting Cover Crops found that less than 2% of cropland in the Mississippi River Basin is planted to cover crops. 

Cover crops also replenish the soil. “If we want to grow 300-bushel corn, we need 300-bushel-per-acre soil,” Wolf says.

Decades of voluntary efforts have failed to gain enough traction to curb calls for federal regulations. Weather extremes also are raising serious concerns. In 2013, much of the Corn Belt was inundated with more than 16 inches of rain from April through June.

“You hear comments that if farmers applied the right amount of nitrogen at the right time, there wouldn’t be water-quality problems,” says Matt Helmers, ISU ag and biosystems engineering. “It’s a misconception that we can solve all of our problems by better nitrogen management in the field. It has to start there, but we absolutely have to look beyond that.”

Algae blooms have staked out an average of 6,700 square miles of the Gulf for the past five years. The Hypoxia Task Force, formed in 1997, aims to shrink this zone to 1,930 square miles.

The 2012 Mississippi River/Gulf of Mexico Watershed Nutrient Task Force required task force states to create action plans. However, a new EPA Office of Inspector General audit reports slow state progress and cites a lack of specific timetables and monitoring requirements.

Only three states – Iowa, Minnesota, and Wisconsin – have set nutrient-reduction goals. Minnesota is the only one with a timetable.

Dean Lemke, a 41-year veteran of the Iowa Department of Ag and Land Stewardship, now with the Agribusiness Association of Iowa (AAI), helped write Iowa’s nutrient-reduction strategy. 

“In the long run, we’ve got to move to measure how much of the nutrients are being discharged from farms  and to show progress, just like towns and cities do,” he says. “It’s not as clear-cut and predictable as sewage treatments.”

Iowa’s nutrient-reduction goal is 45% (point and nonpoint sources). “That’s a big number, and we won’t meet it if we continue to do what we’re doing,” ISA’s Roger Wolf says. “We’ll fall short.”

New efforts are under way. At a Hypoxia Task Force meeting last spring, Ag Secretary Tom Vilsack announced $33 million in funds for producers who adopt practices, including cover crops, that improve water quality in 174 designated watersheds. In its third year, the National Water Quality Initiative is expanding its scope to smaller watersheds and targeting high-impact areas: the Mississippi River Basin, Gulf of Mexico, Chesapeake Bay, and the Great Lakes.

Minnesota is the nation’s first test site for a federal pilot program offering farmers incentives to slow erosion and runoff into four watersheds. Farmers will receive financial and technical support. In return for certification, they’ll get protection from tighter water quality rules for 10 years. It could become a national model.

Building a Solid Case for Cover Crops

The 2012 U.S. Ag Census pegged total cover crop acres at 10.3 million. State data suggests a rapid upswing.

A bumper crop of cover crop research is creating buzz, indicating cover crops are a potential ace in the hole to help farmers gain the upper hand.

“With tillage reduction, you can reduce surface runoff, phosphorus, and erosion,” ISU’s Matt Helmers says. “Over the past 20 years at our research farms, we’ve seen similar nitrate concentration loads coming out of field tile with no-till and conventional tillage. 

“As we work on in-field management with farmers, cover crops have to be a major player to reduce nutrient loads in downstream waters,” he says.

Studies in Iowa show an annual nitrate-leaching reduction of 10% to 60% when comparing a corn-soybean rotation with a winter rye cover crop to a corn-soybean system without a cover crop. “The cover crop also can have benefits in reducing surface runoff and loss of associated sediment and nutrients,” he says. “It’s likely to depend on soil type, amount of cover crop growth, and how and when the crop is terminated.”

In a dry year, Helmers says farmers may worry a cover crop will use up soil moisture needed for the cash crop. “Based on our research for one year,  the cover crop provided mulching and shading effects after it was terminated,” he says. “More research is needed.”

In southeastern Indiana, a long-term study shows the combined effect of cover crops and a reduction in N fertilizer rate, lowering nitrate losses in tile drains.

“When you get a good cover crop established, it reduces nitrate loss out the bottom of the root zone and into tile drains,” says Eileen Kladivko, Purdue University agronomist and cofounder of the Midwest Cover Crops Council.

The Cover Crop Group in USDA’s Sustainable Corn Project is field testing a winter rye cover crop at 10 sites in six Midwestern states. The project is a combined effort of 10 land-grant universities, the USDA’s Ag Research Service, and farmers in the upper Midwest. The cover crop study will wrap up in 2015.

Practical Farmers of Iowa (PFI) took an early lead on cover crops. By 2008, it began partnering with Iowa Learning Farms, the National Laboratory for Agriculture and the Environment, and the Leopold Center to create the Iowa Cover Crop Working Group.

PFI recruits farmers for on-farm research and to host field days to show new practices and technology. PFI has held or supported 100 field days in 2014, attracting 80 to 120 people per event.

“Attendance has gone through the roof,” says Sarah Carlson, PFI Midwest cover crop research coordinator. “We’ve been fielding a lot of questions from farmers who aren’t our members.” (Visit

Despite this interest, many farmers hesitate. Others may have had a bad experience, possibly related to weather.

“We have many questions to address, including where the seed will come from, availability of equipment, and labor and management,” Wolf says. Other critical issues include:

Improving strategies for planting and terminating cover crops

• Maximizing biomass production

• Reducing interference with harvested crop

Cover crops require less long-range investment and commitment than a wetland or bioreactor. But there’s still a cost.

Cover Crop Cost Calculator

Download the Excel file to calculate the total cost of using a cover crop including seed, application, and chemical termination. The cost of drilling and aerial application is calculated for comparison. Any cell shaded in yellow can have a value inserted, including the cost of the seed in dollars per pound and the cost of the application. 

Find the calculator at

Emerging research suggests that farmers could recoup all or part of this cost. A Purdue University study (Synergies Between Cover Crops and Corn Stover Removal) indicates that cover crops may boost corn stover removal rates while maintaining soil quality when stover is harvested.  

Cover crops also are attracting attention as forage for late-fall and early-spring grazing. “Livestock producers find that keeping the soil covered is great for water quality, and using the forage makes the bottom line better,” PFI’s Carlson says. “Corn and rye silage is great for feedlot operators, and grazing a spring rye cover crop helps reduce pressure on permanent pastures. Hog and dairy producers achieve better nutrient capture by injecting nutrients into green cover instead of black soil.”

Over time, cover crops also pay off by building organic matter and soil health. Growing diverse crops with different life cycles makes it harder for weeds to grow.

Steve Berger, Wellman, Iowa, draws upon 36 years of cover crop and no-till experience. “It’s a different management system,” he says. “The root system changes as fungi attach to it and aerate soil structure over time. Soil porosity increases, decreasing compaction and increasing water infiltration. This reduces runoff and erosion.”

Berger’s average corn yields are 20 bushels above his county average; 5 to 10 bushels above the average for soybeans.

He surface-applies nitrogen after harvest to help microbes digest the extra residue in preparation for next spring’s corn. He also cautions that farmers should scout their fields and be prepared to control insects, at least initially.

“Cover crops can be a habitat for both pests and beneficial insects,” says Matthew O’Neal, ISU entomologist.

About 40% of U.S. farmland is rented. That means landowners must be on board with cover crop efforts. Cost-share funds help to defray fixed costs, but other agreements are needed.

Near Jefferson, Iowa, David Ausberger is seeding rye and mixing in a few radishes for his fifth cover crop. “I’m still learning,” he says. “I’ve been contacted by landowners because I’m involved with no-till and cover crops. They see land as an investment, but they also want to be stewards of the land and improve it for the next generation.”

Ausberger is working with Tracy Blackmer, Cover Crop Solutions, LLC, Lititz, Pennsylvania, to create a 160-acre national test plot on Ausberger’s farm.

“It’ll be a comprehensive effort to come up with science-based numbers, determine what strategies work best to improve soil, manage nutrients and herbicides, and increase yields,” Ausberger says. “We hope to generate good results and invite people to come and learn. If we get hard numbers, it’ll be easier for others to adopt. The nutrient-reduction strategy is a big part of it.” 

For more cover crop trial results, check ISA’s On-Farm Network database at

Tips for Getting Started

1. Start small. Begin with one field or part of a field. Observe how it affects your production.

2. Match cover crops to your individual farm. What do you want cover crops to accomplish?

3. Study and plan your seeding strategies. Ground seeding, aerial seeding, and grain drills are three different strategies.

4. Calculate your costs ($20 to $40 per acre). The least expensive is oats; radishes and legumes cost the most.

5. Manage cover crops like a cash crop. Plant in a timely manner and kill the crop at the optimal time (two weeks prior to planting corn).

Cover crop acres in Iowa have grown from fewer than 10,000 acres in 2009 to an estimated 450,000 acres in 2013-14. Yet, that’s only about 2% of the state’s total farm acres. 

“For the Iowa Water Quality Initiative to succeed, 5 to 6 million acres must be seeded in cover crops in the next decade,” Wolf says. “That’s more than 25% of working cropland.”

It’s a challenge in an ag economy that’s tightening its belt. “Many cover crop benefits require several years to build up,” Purdue’s Kladivko says. “Producers need to keep the long view in mind.” See for a cover crop decision tool.

Helmers agrees. “These aren’t short-term financial gains,” he says. “Without reduced nitrogen and phosphorus export, we may see regulations.”

In 2010, EPA set a total maximum daily load for the Chesapeake Bay watershed, with a goal establishing 60% of the management practices for nitrogen, phosphorus, and sediment runoff in place by 2017. Since 2006, cover crop acres in the Chesapeake Watershed have jumped from 12% to 52%.

“Regulation imposes very basic requirements, and a one-size-fits-all ultimately becomes a one-size-fits-none,” says Lemke, AAI’s director of nutrient management and environmental stewardship. “It required 150 years for Gulf hypoxia to happen. Water is part of a big ecosystem, and it will take a long time to see improvements. We’re an instantaneous culture; we want a quick fix.”

New Partners Needed

The complexity of the challenge demands a full-throttle offense by agribusinesses, government, university researchers, and other stakeholders.

Fred Yoder, a Plain City, Ohio, farmer and former National Corn Growers Association president, says equipment innovation will spur cover crop adoption.“With new and improved machinery, you’ll see more mainstream acceptance,” he says. “Farmers are good at adapting.”

Illinois farmer Don Birky and his son, Matt, added hydraulics to a Rogator, elevating it about 11 feet above the corn. It’s being used to seed cover crops, and a patent is pending.

Near Fairbury, Illinois, last summer, the Indian Creek Watershed Project Tour showcased unmanned aerial vehicles and Rowbots that planted cover crops between corn rows. It was hosted by the Conservation Technology Information Center (CTIC) and the Livingston County Soil and Water Conservation District at the Marcus Maier farm near Forrest.

The Indian Creek project is part of the Mississippi River Basin Initiative. “On the state level, we’ve found EPA sees a farmer’s point of view and isn’t here to put a big foot down,” Maier says. “It wants a solution that works for everyone.”

A 2014 survey by CTIC and USDA’s Sustainable Agriculture Research and Education reveals farmers want ag retailers to monitor soil health and to offer cover crop advice.

Agren, Inc. of Carroll, Iowa, a conservation services business founded by Tom and Stan Buman, is teaming up with United Supplier, a member-owned wholesaler for 700 elevator groups and other retailers in 20 states and two Canadian provinces. “Ag suppliers and consultants are key to accelerating cover crops and other water-quality practices,” Tom Buman says.

In Sioux County, Iowa, the Farmers Co-op Society is working with farmers, the Iowa Farm Bureau, and Iowa Pork Producers in the watershed of the West Branch of the Floyd River. Funded by the Iowa Department of Ag and Land Stewardship and the Iowa Department of Natural Resources, the group is setting up plots to demonstrate how manure applications fit with cover crops as well as the effectiveness of injecting manure with knives to reduce soil disturbance.

Diverse Alliances Also Play a Role 

Avoiding algae blooms like the one threatening Toledo’s water supply requires long-term solutions with a strategically coordinated approach, says Suzy Friedman, director of ag sustainability, Environmental Defense Fund.

The Nature Conservancy of Illinois, the NRCS, and University of Illinois are working together at the Franklin Research and Demonstration Farm in the Mackinaw River Watershed.

“We’re doing trials of cereal rye, annual ryegrass, radishes, and other covers to see if they scavenge nitrogen and improve water quality,” says Maria Lemke, Conservancy ecologist.

Weather extremes also may catapult cover crops onto the fast track. “The system is leaky,” points out Robert Anex, University of Wisconsin professor and Sustainable Corn Project leader. “Spring precipitation is increasing, with more intense rain when risk of nitrate loss is greatest.”

Across the U.S., nitrogen runoff into rivers and lakes is racking up huge bills at urban water-treatment plants. 

Cover crops can help, PFI’s Carlson says. “We know how to measure nitrogen, so we’ve assumed changing nitrogen alone will improve water quality,” she says. “It isn’t the solution. We’re paying for the loss of a winter root system. We need a mix of warm- and cool-season crops and roots growing in the ground year-round to restore carbon and to protect the soil.”

Soil is agriculture’s number one resource, Berger says. “We need to keep and build our capital assets,” he says.

ISU professor Rick Cruse is working on a new model that shows soil loss exceeding the average estimate of 5.4 tons per acre per year.

 “Soil erosion reduces crop yield,” Cruse says. “We’re eroding soil faster than it’s forming.”

Saving soil was on Iowa farmer Kadolph’s mind at a September cover crop meeting cosponsored by SFWA. He opted to seed cereal rye on the rolling ground once farmed by his grandpa and great-grandpa. Someday, he hopes that his son, Kurtis, 30, will be the fifth generation.

“I’d like to plant more cover crops next year, but this is a good start,” he says.

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